Technical Field
The present invention relates to photovoltaic devices, and more particularly to a conductive electrode having increased thickness and roughness to reduce and virtually eliminate surface reflection.
Description of the Related Art
With growing concern about low cost clean energy, solar power has again become a focal point for alternatives to fossil fuel energy production. Solar energy, while clean and sustainable, typically relies on expensive technologies for its implementation. These technologies include the incorporation of integrated circuits or integrated circuit technology into the fabrication of solar cells. The expense associated with current solar panels is a strong disincentive from moving in the direction of solar power.
Solar panels employ photovoltaic cells to generate current flow. When a photon hits a solar cell, the photon may be transmitted through, reflected off, or absorbed by the solar cell if the photon energy is higher than the material band gap value. This generates an electron-hole pair and sometimes heat, depending on the band structure. The greater the absorption the greater the efficiency of the cell.
Textured structures have been employed to increase the absorption efficiency. However, challenges arise at several points in the process. One such problem includes the formation of a bottom electrode. A bottom electrode deposition occurs by forming a layer of electrode material and deep reactive ion etching (DRIE) the material to attempt to conform the bottom electrode material to the shape of the underlying structure. DRIE is a highly anisotropic etch process making the formation of the bottom electrode highly sensitive to thickness variations. A bottom electrode that is too thin results in series resistance problems and affects the efficiency of the solar cell.